No strings attached: Why are men more interested in casual sex?

First, is there any truth in [gender] stereotypes? And second, if there is, why?

The answer to the first question, in my view, is an unequivocal yes: A mountain of evidence suggests that the sexes do differ – on average – in their interest in casual sex and sexual variety. This evidence, which I explore in some depth in my new book The Ape That Understood the Universe, includes self-report survey responses, analyses of real-world behaviour, and anthropological and historical records. In this essay, though, I’d like to focus on the second question: the why question. Why are men more interested than women in uncommitted sex and sexual variety? On one side of the debate are those who argue that it’s all down to social pressure, socialization, and culture. On the other side are those who argue that, even if these factors nudge things around a little, or even a lot, the ultimate roots of the difference lie deep in our evolutionary past.

Cultural forces clearly influence people’s willingness to engage in casual sex, and to some extent their desire to do so as well. But the idea that culture creates these sex differences out of nothing not only clashes with the available evidence, it clashes with everything we know about how evolution works.